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Peacemakers 6dof Unicorn Build

Discussion in 'DIY Motion Simulator Projects' started by Peacemaker105, Oct 5, 2018.

  1. Gadget999

    Gadget999 Active Member

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    My Motion Simulator:
    2DOF, DC motor, Arduino, 6DOF
    more torque and same inertia for less money - bargain

    i found the seller here -- https://www.aliexpress.com/item/323...earchweb0_0,searchweb201602_,searchweb201603_

    sadly the shipping to uk is nearly £100

    hope you get the huming sorted out, do you need more pulses for the encoder or a higher frequency of pwm ?
  2. Peacemaker105

    Peacemaker105 Active Member Gold Contributor

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    Not sure yet i gave up for the day yesterday and now im working for a few days. I'm in contact with the guy who did the guide now asking for his settings etc and also if he gets same vibes.. Worst case i will try the 10,000 PPR encoder from Mige for US$89 delivered.

    Yes my shipping was almost as much.. but check this link.. same seller but $100 cheaper for some reason haha. it says 10025 motor in description but everything else says 10015 even the specs. plus they sent me the right one.
    https://www.aliexpress.com/item/32868662195.html?spm=a2g0s.9042311.0.0.67274c4d5qpWWV

    Chris.
    Last edited: May 5, 2020
  3. Thanos

    Thanos Building the Future one AC Servo at a time... or 6

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    Hey Chris, these AASD servos already have 10000 pulses per revolution encoders on them. I use pulses to control them that matches that resolution.

    So what is happening if you get less pulses encoder resolution per rotation, is that you set a divider in the parameters for the encoder outputs on the db25... check your parameters mate!

    IMG_20200504_213654.jpg
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    Last edited: May 5, 2020
  4. Peacemaker105

    Peacemaker105 Active Member Gold Contributor

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    Cheers for chiming in Thanos,

    So if i understand this correctly.. can i use a divider of 4 and have an equivalent of 40,000 pulses per revolution? Or am i way off? haha
    Last edited: May 5, 2020
  5. lromaniuk

    lromaniuk bny

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    Yes you can get 10.000 (max) positions per revolution with this servo. but:

    The encoder on those servos is actually 2500 PPR (pulses per revolution). But after quadrature decoding A B signals you can get 10.000 CPR (counts per revolution). See the link below to read about PPR and CPR difference https://www.cuidevices.com/blog/what-is-encoder-ppr-cpr-and-lpr

    I used STM32F1 (BluePill) controller which has built in harware quadrature decoder to obtain shaft position (the same Thanos was using some time ago on his Encoder2Positon module).


    Cheers.
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  6. Peacemaker105

    Peacemaker105 Active Member Gold Contributor

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    Ok, yeah that makes sense. Now i guess the question i should really be asking @Thanos is what values should be in PN016 and PN017 to achieve maximum resolution? I just assumed the stm32f4 board would be reading the A+B pulses and doing the quadrature for me?

    I have input 10,000 in MMOS software and it seems to show me the correct resolution when running wheel check.. I just read in the forums that going from 10000 to 40000cpr is a massive upgrade for the mige osw, hence why i thought it might be the lower resolution giving me vibrations. Then again.. 10000 is a lot and i would expect it to still be smooth so maybe its EMI or something else going on.. maybe even the game..
  7. Gadget999

    Gadget999 Active Member

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    Hi Chris,

    do you have a link to the guide ?

    Regards
  8. Thanos

    Thanos Building the Future one AC Servo at a time... or 6

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    The max resolution should be with PN016=1 and PN017=1.

    Can you share screenshots of the settings you use in MMOS software to define the control mode? I suspect you are using PWM/Dir mode which is not the same as Pulse/dir mode that the AASD servo needs. The PWM is variable width pulse that can confuse the pulse decoder of the drive or skip pulses if they are of small value treating them as noise...
  9. Peacemaker105

    Peacemaker105 Active Member Gold Contributor

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    • Like Like x 2
    Last edited: May 6, 2020
  10. lromaniuk

    lromaniuk bny

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    @Thanos Foregive my lack of knowledge but shouldn't the servo be driven in torque mode for FFB wheel?

    At least it seems that this software/controller is expecting that - even servo amp parameters are set for analogue torque. The same goes with connection diagram for CN2 (DB25) port where 25th pin is connected and this is for analog voltage input +-10V. Which probably leads us to your hum/vibration. It seems that MMOs firmware is outputting PWM signal which is not compatible (not continious) with servo drive input configuration. The issue is, it seems that it is imposible to drive torque on this servo drive other than those +-10V. What you can try to do is to use some electronic components to transform that PWM signal into analogue that is scaled to +-10V.
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  11. Will974

    Will974 Member

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    Hi,

    Is it possible to have more details about the component that you use to connect the carbon tube with the rod end bearing ?
    Is it a standard component ? If yes, can i have the link of the seller please ?

    Thank you very much ;-)
  12. Peacemaker105

    Peacemaker105 Active Member Gold Contributor

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    Here is the long awaited build video of one of my Actuators. Hopefully it clears it a few things up :)
    One of my nuts came of the back of the ballscrew at the bearing and when i hit the E-stop it came crashing down and dislodged it from the coupler (all explained at the end of the video).. anyway easy fix and good opportunity to look at the components after 50 odd hours of abuse and also do a build video :) I'm happy to confirm everything is great on the inside! I'm Stoked with how these have been performing.

    @Will974 Sorry mate didn't see your question. This video will answer your question in more detail. Short answer is it's a piece of Steam pipe machined out to fit the two components and epoxied in place.

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  13. Will974

    Will974 Member

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    Hi,

    Thanks a lot for your answer and this video. I'm going to watch it conscientiously :)

    Will
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  14. Will974

    Will974 Member

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    Hi,

    I am interested me to the dimensions of your rig and i was surprise.Center to center, the lower base (1240 mm) is smaller than the upper base (1380 mm) . Usually it's the reverse. So, it is not a conventional dimension comparing to the other rig that we can see on xsimulator. Why did you make this choice ? Is to have more angular stroke or just to limit the clutter of the lower base ?
  15. JEM

    JEM New Member

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    Great work!

    Can you share the size of the heim / rose / ball joints up top on the actuators?
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  16. Peacemaker105

    Peacemaker105 Active Member Gold Contributor

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    Sure, they are M10 Male thread. I also run some M10-M8 rod end misalignment spacers (2 for each rose joint).
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  17. JEM

    JEM New Member

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    Thanks for the quick response. I'm researching and beginning the design work for a 6dof. I am leaning towards going the planetary gearbox route VS the linear actuators.

    I have seen a few planetary designs and they all use much larger heim / rose joints. The metric equivalent of M21 or larger with spacer reducers down to about M16 equivalent.

    You may not be able to answer, but I am wondering if you would think larger rose joints would be needed with the planetary route VS the linear route?
  18. Peacemaker105

    Peacemaker105 Active Member Gold Contributor

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    Initially i was going to have the bottom and top triangle the same size and then thought i would make the top a bit bigger so the actuators flex away from my upper platform a bit more. No real science involved in my thinking other than when i was running things through my head it made sense at the time haha. I was also working off some guys talking about trying to achieve a roughly 60deg angle. Cant remember where i read that, probably silentchills build.
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  19. Will974

    Will974 Member

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    Hi,
    Thanks for your answer. So how many degrees do you have on your rig in the pitch motion ?
    On my ring, i can have a maximum - 30 deg and + 32,85 ,so, an angular stroke : 30+32,85 = 62,85 deg.
  20. Peacemaker105

    Peacemaker105 Active Member Gold Contributor

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    Ahh the joys of 600mm balscrews huh?! haha. I have about 15 degrees either way at 300mm stroke. Soon i will raise the stroke to 350mm which should give me a couple more. Ideally, i just need more stroke.
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